Ok, well to do it properly it first needs some new novels and a set of railroady adventures based on them.
Just kidding.
I'm not sure what could get me to buy into DL...??
IME the best product ever produced was the 5th Age/Saga edition's Bestiary (best MM, ever). I read up on the lore of the 5th Age before the WotL because we uniformly rejected the early modules when they were originally published, and It took me until about 1997 or so to circle back around. I picked up some of the 5th Age boxes and the TotL box (then read the original trilogy) , some of the classic reprints in 2E format, and eventually the 3E book when it came out (which I found a complete snoozefest and perfect example of how not to write a setting guide-killed my enthusiasm nearly 100% for ever running DL).
As a usable game setting at the time I really liked the 5th Age lore that was presented in Saga, and lack of Iconic characters. Much moreso than what I was reading about the WotL era.
I DO agree with
@Wolfpack48 above. The way the dragons were presented and used in the adventures as a centerpiece and as villains all their own instead of just a (pick your color) dragon.
I also think the setting would have to focus outside of the WotL and especially avoid Iconic characters and mention them/their deeds only in passing. It has to present a new hook and motivations for people's home games. The 5th Age was not terribly popular with fans. Are there other Ages that can be tapped into?
And unlike what WOTC has done with GH and especially FR- they would have to stay true to the setting- no shoehorning dragonborn in as a replacement for draconians or sime kind of "new" species, no tieflings, no halflings, etc etc. No more homogenized "shared experience" where the PHB takes precedence over the Setting.